1, communication confidentiality stage: the main focus is on communication security, to ensure that information is not eavesdropped or tampered with during transmission. This phase began in the early days of communications technology, especially in the field of military and diplomatic communications, and landmark events include the application of cryptography during World War II and the theory of confidential communications proposed by Shannon.

2, computer security stage: with the widespread application of computer technology, the focus of information security has shifted to the security of computer systems, including operating system security, database security, network transmission security. This stage from the 1970s to the 1990s, accompanied by the emergence of computer viruses, the development of firewall technology and the progress of cryptographic algorithms.

3. Information security stage: the concept of information security is gradually improved, covering many aspects such as confidentiality, integrity, availability, non-repudiation and controllability of information. This stage is not only concerned about physical security, but also began to pay attention to logical security, software security, network security and other issues, the introduction of ISO27001 and other information security management system standards.

4, information security stage: further put forward the concept of information security, emphasizing the protection, detection, response, recovery and other all-round security of information systems. This stage pays more attention to security management, disaster recovery, emergency response and other practical operational level, as well as laws and regulations, organizational structure, personnel training and other aspects of security construction.

5, cyberspace security stage: with the popularization of the Internet and the advent of the mobile Internet era, cyberspace security has become a new focus. This stage not only has to deal with traditional information security threats, but also has to face emerging challenges such as APT attacks, DDoS attacks, IoT security, cloud computing security, big data security, etc., and at the same time, it also promotes the introduction of national-level cybersecurity strategies and regulations.

6, Trusted Computing Stage: Focus on building a trusted computing environment based on hardware and chain of trust, establishing a full life cycle chain of trust from hardware, firmware, operating system to application layer to ensure that the entire information system is safe and trustworthy from the underlying hardware to the upper layer of applications.